Now he's in charge of the Texans, who went 2-14 last season and hold the draft's No. 1 overall pick. The external pressure on O'Brien and general manager Rick Smith to draft Manziel - a native of Tyler, Texas, and the 2012 Heisman Trophy winner at Texas A&M - will be immeasurable, and Manziel was happy to use his leverage within his home state to add to that pressure Friday.
"I'm a Texas guy, born and raised in Texas," he said. "I've never really left the state, so for them to have the first pick means a lot to me."
O'Brien wasn't biting on the bait. He revealed little about the Texans' intentions, and he dismissed the idea that the mania surrounding Manziel would influence the team's decision, though picking Manziel sure would make good business sense. The Texans compete for attention within the most football-crazy state in America and with the most popular football franchise in America - the Dallas Cowboys. So drafting the most popular football player in Texas would immediately afford them a cachet they've really never had.
"I don't worry about those things," O'Brien said. "We concern ourselves with doing what's best for the organization, what's best for our team, which player at any position fits what we're going to do. Is he going to be in the building all the time? Is he going to eat, breathe, and sleep football? To me, when you play in this league, that's the type of players who have success in this league."
Those are the questions that still hover around Manziel, infamous for his pell-mell behavior off the field and incandescent for exhibiting similar qualities on it, as if he were the product of a gene-splice experiment involving Bobby Layne and Archie Manning. It created some murmurs Friday that Manziel measured less than 6 feet tall, but each of his hands is 97/8 inches long, the largest of any quarterback at the combine, and he weighs 207 pounds.
He would seem to possess the physical traits to overcome the perception that O'Brien, who coached 6-foot-4 Tom Brady with the New England Patriots and 6-foot-4 Christian Hackenberg at Penn State, prefers the traditional quarterback prototype: tall, strong-armed, nimble in the pocket but reluctant to venture outside it.
"There's no way that you label yourself, that you like this type of quarterback over that type of quarterback," O'Brien said. "In my career, I've been around quarterbacks that were 6-foot-5, and I've been around quarterbacks that were 5-foot-10. Both types of quarterbacks were very successful with some of the things we did offensively."
In so many words, then, O'Brien and the Texans may draft a quarterback. Or they may not. If they do, they may take Manziel. Or Louisville's Teddy Bridgewater. Or Central Florida's Blake Bortles. For O'Brien, this is the joy of being back in the NFL. No labyrinth of NCAA regulations to negotiate. No balance to strike among the oft-competing priorities of college sports. No Paterno legacy either to uphold or cast into history. Just football now. Sit in the bleachers at the combine, pop in the tape when you get back to Houston, and evaluate what you see. Everything else is a nuisance.
"I love Penn State," he said. "Enjoyed the players I coached there. I think it's a great school. I think it's a fantastic school. Student body's great. I felt like this was an opportunity . . . that we couldn't pass up."
It was where he always wanted to be, and he gets to make some kind of entrance. He gets to make the kind of decision that can define a franchise and a coaching career. From Johnny Manziel to the rest of the NFL to the entire state of Texas, everyone's waiting on Bill O'Brien now.